(1) Field of the Invention
The present invention relates to a superconducting synchrocyclotron. In particular the present invention relates to a synchrocyclotron with a novel main magnet excitation system which has a superconducting coil. The invention was supported by National Science Foundation Grant PHY-8312245.
(2) Prior Art
The synchrocyclotron is an apparatus which, employs the resonance principle of the cyclotron. Indeed, in its simplest form the synchrocyclotron differs from the cyclotron only in that the acceleration system is modulated in frequency to match the mass of the accelerated particle. A cyclotron operates successfully only when the mass of the ions remains constant, that is, so long as the speed of the ions is negligible as compared with the speed of light. When the mass begins to increase, the ions fall out of step with the electric field and gain no more energy from it. In the synchrocyclotron these restrictions are circumvented by periodically decreasing the frequency of oscillation, f, of the acceleration system. The beam of ions then emerges as a series of pulses, one for each decrease in the frequency of oscillation.
Synchrocyclotrons, also called frequency modulated cyclotrons, have been used for many years for the acceleration of light ions i.e. protons, deuterons, and alpha particles. Some light heavier ions such as carbon have also been accelerated in synchrocyclotrons. Overall, when requirements on beam intensity and precision are modest, the synchrocyclotron tends to be a competitive choice over the ioschronous cyclotron in the general energy range of 1 GeV and below. This is principally due to the fact that the synchrocyclotron is considerably less complicated than an isochronous cyclotron with fewer precision parts and is therefore less costly.
In recent years the successful medical use of proton and alpha beams from synchrocyclotrons for treatment of diseases of the eye and of the pituitary gland in humans has led to consideration of possible wide use of these ion accelerators in hospitals, In this and other applications, if a superconducting synchrocyclotron could be substituted for the conventional non-superconducting synchrocyclotron, the overall accelerator system would be much smaller, easier to install, and total cost would be reduced by a large factor.